Impact of intermittent polarization on electrode-respiring Geobacter sulfurreducens biofilms
By Guo, Fei; Babauta, Jerome T.; Beyenal, Haluk
Published in Journal of Power Sources
2018
Abstract
In practice, electrochemically active bacteria such as Geobacter sulfurreducens do not generally have uninterrupted access to a polarized electrode to transfer electrons. This is because many strategies for harvesting energy from these bacteria to power electrical devices rely on intermittent operation. Thus, understanding how electrochemically active bacteria respond to intermittent polarization can improve future energy-harvesting technologies. The goal of this work is to determine the change in electron transfer rates of electrode-respiring G. sulfurreducens biofilms exposed to conditions of intermittent polarization. Intermittent polarization is simulated using cycles of polarization and open circuit of varying durations, or pulse widths. Compared with an 18-day baseline current, an elevated current response is observed for pulse widths less than 5 min. The elevated current response reaches a maximum of 1.9 mA for a 0.5-min pulse width. Impedance analysis used to separate resistive and capacitive behavior suggests that intermittent polarization results in an increase in total resistance at pulse widths greater than 5 min. Changes in biofilm capacitive behavior are found to be negligible.